A block copolymer has a molecular structure in which polymer blocks having different chemical structures are linked by covalent bonds. The block copolymer may form a periodically arranged structure such as a sphere, a cylinder or a lamella through phase separation. The shape and size of a domain of the structure formed by self assembly of the block copolymer may be controlled in a wide range by, for example, the type of a monomer forming each block or the relative ratio of blocks.
Due to such a characteristic, the block copolymer is considered to be applied to lithographic process that can manufacture nanowires, manufacture various next generation nano elements such as quantum dots or metal dots, or form a high density pattern on a predetermined substrate (e.g., refer to Non-patent document 1).
The technology of controlling orientation of the structure in which the block copolymers are self-assembled on various types of substrates horizontally or vertically is a very big part of practical application of the block copolymer. Conventionally, the orientation of a nano structure on a film of the block copolymer is determined by which block is exposed to a surface or in the air. Generally, since a plurality of substrates are polar and the air is non-polar, among blocks of the block copolymer, a block having a higher polarity is wetted on a substrate, and a block having a lower polarity is wetted at an interface between the block and the air. Accordingly, to simultaneously wet blocks of the block copolymer, which have different characteristics, on a substrate, various techniques are suggested, and the most typical technique is control of orientation through manufacture of a neutral surface.